Emission node not rendering at all in Cycles nor Eevee
Note: the solution I found, for whatever reason, only works in Eevee. So, if anyone has a better answer that also works in Cycles, please share it :D
Thanks to all the people who commented on my question, I figured out that the emission was converted to color and thus wouldn't emit any light. The only way to get the pupil to emit light again was to turn it back into a shader. Here's how I did it:
Take the &quot;B&quot; (in my case) from the separate RGB &gt; Emission (strength) &gt; Shader to RGB &gt; Emission (in the Principled BSDF) (put color to color, not alpha to color)

Like I said, this only works in Eevee. The result should look something like this: